Mandrel problem

[ebarr]

OK, I Took EagleSC's advise and purchased a spare mandrel. Which by the way is great advise.

I turned my first pen on it over the weekend. While turning the lower barrel I noticed a slight wobble in the blank. I have had this similar problem with my other mandrel. I am very careful not to overtighten my blanks. I don't think that was the issure.

I then got creative, stole DaveO's handmade center ring idea and turned a center ring on my upper barrel. I thought I did a pretty good job on the turnings until I went to put them together. The barrels did not line up :BangHead:

After quite a while of gentle and light persuasion (yea right) I managed to crack the blank.

Is the wobble my problem source? I seem to have this problem on both my mandrels, but the newer one is worse.

Any advise would help.



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[woodArtz]

Hi Wayne,
Have you confirmed that the points on your head stock and tailstock line up point to point. I know on my older Jet lathe with the swiveling head, I had to realign the center after moving the head. It made a huge difference. I also check my mandrels by lightly marking with a pencil in one spot. If the mandrel is perfectly straight, the pencil mark will go all the way around, if not then you'll get a half circle. I hope that helps.

Bob

 

[ebarr]

Haven't checked the lining up my head stock and tail stock. I will check this tonight.

Thanks,

 

[Eaglesc]

Before you mess with the head stock, make sure the INSIDE of the MT on the head stock is clean.
Spray some wd 40,marvel mystery oil or carb cleaner in the MT.
Roll up some paper towels and turn the handwheel or set it on the slow speed and kind of "ream it out".
See if the towels are clean.
Blow out the MT.
Do this before you do anything else.
Are your bushings clean? any CA residue on the ends?
When you milled the blanks did you "peen" over the brass?
Put the mandrel in.
Is there a vibration before you tighten the thumb screw?

 

[clowman]

I'd second Eagle's recommendation on making sure the blanks were square. I had that problem before. I'm a little slower than others, so it took me about a dozen pens to realize my mistake....

 

[ebarr]

Everything cleaned and blown out.

I did put a live center in the tailstock and matched up both head and tail stock. The tail stock was off just enough to see. It amost looks like the point has been bent slightly. This is where I may start.